WAVES
Sound
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Sound Video Links
of the Bells –Explanation
 Water Glasses
 Auto-Tune
 Carol
2
Background Information
1. Longitudinal waves – move in and out by
compressing together
(Example: Sound Waves, slinky)
– Parts
• Compression – close together
• Rarefaction – far apart
Compression
Rarefaction
3
4
What Is Sound?
 Sound
is vibrations.
 Molecules
COMPRESS and
bump into each
other!
•Ex: Air particles
compress and
spread out until
 (Without molecules or they meet your
substance… there can EAR!
be no sound!)
5
Sound Depends On:
1.
2.
3.
A vibrating
source to make
waves
A medium to
carry the waves
A receiver to
detect them
6
Can sound travel in empty space??
 No!
Sound can’t because there is no
medium or particles to BUMP into!
Light can travel through space because it is
like a particle
and a wave!
(Particle-wave duality
nature of light)
7
Sound Vibrations
 Back-and-forth
PARALLEL
 Sound
travels away
from the vibrating
object in radially all
directions.
8
Sound waves travel at all directions until it
reaches a surface where it is absorbed or
reflected.

This is how sound waves normally travel from one source.
9
Sound waves from a tuning fork.
 As
the fork
vibrates it
causes
particles to
compress
and rarefact
(spread out)
10
What is the speed of
sound?
 Through
Air: 343 m/s @ 20º C
11
Sound Travels at Different Speeds
Through Different Materials
 Meters
per second
20,000
18,000
16,000
14,000
12,000
10,000
8,000
6,000
4,000
2,000
0
WATER
GRANITE
Sound Travels faster through SOLIDS!!!
12
Which Would Be the Best
Conductor of sound?

Solid?
 Liquid?
 Gas?
– The
Bricks!
 Solid
13
What mediums does sound
travel through?
SOLIDS – Fastest speed
2. LIQUIDS – Medium speed
3. GAS – Slowest speed
4. VACUUM – N/A (Doesn’t go
through it)
1.
*This is key information to memorize
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What happens when you
change the AMPLITUDE?

Changes the VOLUME
(loudness)!

Amplitude (loudness) also
depends on:


Distance from the source.
The energy will decrease
and get softer as you move
away
 Sound
Volume Control
simulation
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What happens when you
change the FREQUENCY?
The Higher the Frequency the Higher the Pitch.
The Lower the Frequency the Lower the Pitch.
 Depends on how fast the source of the sound is
vibrating
 Sound simulation
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Doppler Effect

Sound is made
from a moving
source
 Sound travels
away from or
toward you.

Toward: higher
pitch
 Away: lower
pitch
 Ex: Car going by
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
To locate a target, a
submarine uses
SONAR (sound
navigation and
ranging).

SONAR emits pulses
of sound waves that
travel through the
water, reflect off the
target and return to
the ship. By knowing
the speed of sound in
water and the time for
the sound wave to
travel to the target
and back, the
computers can quickly
calculate distance
between the
submarine and the
target
SONAR
Whales, dolphins and bats use
the same technique for
locating prey (echolocation).
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High
energy waves have…
1. High Amplitude
2. High Frequency
3. Short Wavelength
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